Smith's test is used to detect?

Appeared in: RUHS, Jaipur, M.Sc Nursing Entrance Exam-2019

Explanation

Smith's test is specifically designed to detect bile pigments in urine.
The test relies on an oxidation reaction. Iodine solution is used as the oxidizing agent.
When bile pigments (bilirubin) are present, the iodine oxidizes them to biliverdin.
This reaction produces a characteristic emerald-green ring at the junction of the urine and the iodine solution, confirming a positive result.

Option B: Acetone, a type of ketone body, is not detected by Smith's test.
Option C: Bile salts are detected by a different test that assesses changes in surface tension.
Option D: Albumin is a protein, and its presence (proteinuria) is detected by tests that cause protein coagulation.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Biochemical tests for urine analysis as background academic context rather than a clinical decision trigger.
The presence of bile pigments in urine (bilirubinuria) is a significant clinical finding that points towards liver dysfunction or biliary tract obstruction.
It suggests that conjugated bilirubin is entering the bloodstream and being filtered by the kidneys, which is abnormal. This is commonly seen in conditions like hepatitis, cirrhosis, or gallstones blocking the bile duct.
A nurse observing a positive Smith's test should promptly report the finding, monitor the patient for other signs of jaundice (yellowing of skin and eyes), and assess for abdominal pain or changes in stool color (clay-colored stools).

How to Approach the Question

This is a direct factual recall question from biochemistry.
First, identify the core of the question: What substance does Smith's test detect?
Recall the common urine analysis tests and the specific substances they identify.
Associate 'Smith's test' with 'bile pigments'. A helpful mnemonic is 'Smith sees green,' referring to the green biliverdin ring.
Eliminate the other options by recalling their corresponding tests: Acetone (Rothera's), Bile salt (Hay's), and Albumin (Heller's or heat coagulation).
Select the option that correctly matches the test with the substance.

Concept Tested & Keywords

QGlz5t-bcobTgEHdi-CyXD

E6 Biochemistry U Satyanarayana— Part 2 (pp 421-820 of 840) p. 367-369

E6 Textbook of Biochemistry for medical StudentsDM Vasudevan Part 2 — Subpart A (pp 1-239 of 478) p. 30-32

E6 textbook of Applied Biochemistry and Nutrition & DieteticsHarbans Lal (pp 26-464 of 479) p. 179-181

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